1. Field of the Invention
The present invention relates to a deformable mirror, especially for the compensation of the influences of atmospheric interferences on the propagation or spreading of high energy laser beams, which incorporates a plurality of electrically actuatable actuators or adjusting elements engaging behind the mirror surface of the mirror.
2. Discussion of the Prior Art
A deformable mirror of the type referred to hereinabove has become known with respect to its typical constructional and utilization capabilities from the disclosure of FIG. 1 and FIG. 2 of the article by James E. Harvey and Gary M. Callahan "Wavefront Error Compensation Capabilities of Multiactuator Deformable Mirrors" (SPIE Vol. 141, Adaptive Optical Components, 1978, pages 50 through 57).
In order to avoid complicated actions of the control system, required from such a compensating mirror is a most linearly possible relationship between an actuation of an actuator or adjusting element and the therewith associated localized deformation of the mirror surface. Consequently, an effort is made to provide for the most rigid possible mechanical and most pointedly possible coupling or connection of each adjusting element to the rear side of the mirror plate, whose front side serves as a compensation mirror surface which is located in the path of the beam. However, the mechanical coupling between an actuator or adjusting element and the rear side of the mirror plate, which is constructed as an adhesive connection, necessitates an extremely large contact surface in order to be able to also take up comparatively large tensile forces through the adhesive connection. Hereby, such forces are encountered when at least one adjusting element is deflected within a certain area, the mirror surface will then bulge; however, nearby located adjusting elements because of their actuation will be less or not at all deflected and thereby subjected to tension. Such a large-surfaced contact between of the adjusting element and the rear side of the mirror plate, in the interest of providing an adequate adhesive bond, stands opposite the requirement for localized defined deflecting capabilities in the finest possible distribution or arrangement across the mirror surface, in the interest of obtaining optimum correlation capabilities for compensating distortions in the cross-section of the path of the beam. With respect to the dimensioning of the control circuit for the electrical actuation of the actuators or adjusting elements, it is, moreover, undesirable in that such adhesive bonds or connections possess a certain elasticity in the direction of pressure transmission and, as a result, must be taken into consideration during the design of the control circuit must be considered as disturbing damping and even propagation time influences.